Polypropylene fibres

ABSTRACT

A polypropylene fibre including at least 80% by weight of a first isotactic polypropylene produced by a metallocene catalyst, and from 5 to 20 by weight of a second isotactic polypropylene produced by a Ziegler-Natta catalyst.

The present invention relates to polypropylene fibres and to fabricsproduced from polypropylene fibres.

Polypropylene is well known for the manufacture of fibres, particularlyfor manufacturing non-woven fabrics.

EP-A-0789096 and its corresponding WO-A-97/29225 discloses suchpolypropylene fibres which are made of a blend of syndiotacticpolypropylene (sPP) and isotactic polypropylene (iPP). Thatspecification discloses that by blending from 0.3 to 3% by weight ofsPP, based on the total polypropylene, to form a blend of iPP-sPP, thefibres have increased natural bulk and smoothness, and non-woven fabricsproduced from the fibres have an improved softness. Moreover, thatspecification discloses that such a blend lowers the thermal bondingtemperature of the fibres. Thermal bonding is employed to produce thenon-woven fabrics from the polypropylene fibres. The specificationdiscloses that the isotactic polypropylene comprises a homopolymerformed by the polymerisation of propylene by Ziegler-Natta catalysis.The isotactic polypropylene typically has a weight average molecularweight Mw of from 100,000 to 4,000,000 and a number average molecularweight Mn of from 40,000 to 100,000, with a melting point of from about159 to 169° C. However, the polypropylene fibres produced in accordancewith this specification suffer from the technical problem that theisotactic polypropylene, being made using a Ziegler-Natta catalyst, doesnot have particularly high mechanical properties, particularly tenacity.

WO-A-96/23095 discloses a method for providing a non-woven fabric with awide bonding window in which the non-woven fabric is formed from fibresof a thermoplastic polymer blend including from 0.5 to 25 wt % ofsyndiotactic polypropylene. The syndiotactic polypropylene may beblended with a variety of different polymers, including isotacticpolypropylene. The specification includes a number of examples in whichvarious mixtures of syndiotactic polypropylene with isotacticpolypropylene were produced. The isotactic polypropylene comprisedcommercially available isotactic polypropylene, which is produced usinga Ziegler-Natta catalyst. It is disclosed in the specification that theuse of syndiotactic polypropylene widens the window of temperature overwhich thermal bonding can occur, and lowers the acceptable bondingtemperature.

WO-A-96/23095 also discloses the production of fibres from blendsincluding syndiotactic polypropylene which are either bi-componentfibres or bi-constituent fibres. Bi-component fibres are fibres whichhave been produced from at least two polymers extruded from separateextruders and spun together to form one fibre. Bi-constituent fibres areproduced from at least two polymers extruded from the same extruder as ablend. Both bi-component and bi-constituent fibres are disclosed asbeing used to improve the thermal bonding of Ziegler-Natta polypropylenein non-woven fabrics. In particular, a polymer with a lower meltingpoint compared to the Ziegler-Natta isotactic polypropylene, for examplepolyethylene, random copolymers or terpolymers, is used as the outerpart of the bi-component fibre or blended in the Ziegler-Nattapolypropylene to form the bi-constituent fibre.

EP-A-0634505 discloses improved propylene polymer yarn and articles madetherefrom in which for providing yarn capable of increased shrinkagesyndiotactic polypropylene is blended with isotactic polypropylene withthere being from 5 to 50 parts per weight of syndiotactic polypropylene.It is disclosed that the yarn has increased resiliency and shrinkage,particularly useful in pile fabric and carpeting. It is disclosed thatthe polypropylene blends display a lowering of the heat softeningtemperature and a broadening of the thermal response curve as measuredby differential scanning calorimetry as a consequence of the presence ofsyndiotactic polypropylene.

U.S. Pat. No. 5,269,807 discloses a suture fabricated from syndiotacticpolypropylene exhibiting a greater flexibility than a comparable suturemanufactured from isotactic polypropylene. The syndiotacticpolypropylene may be blended with, inter alia, isotactic polypropylene.

EP-A-0451743 discloses a method for moulding syndiotactic polypropylenein which the syndiotactic polypropylene may be blended with a smallamount of a polypropylene having a substantially isotactic structure. Itis disclosed that fibres may be formed from the polypropylene. It isalso disclosed that the isotactic polypropylene is manufactured by theuse of a catalyst comprising titanium trichloride and an organoaluminiumcompound, or titanium trichloride or titanium tetrachloride supported onmagnesium halide and an organoaluminium compound, i.e. a Ziegler-Nattacatalyst.

EP-A-0414047 discloses polypropylene fibres formed of blends ofsyndiotactic and isotactic polypropylene. The blend includes at least 50parts by weight of the syndiotactic polypropylene and at most 50 partsby weight of the isotactic polypropylene. It is disclosed that theextrudability of the fibres is improved and the fibre stretchingconditions are broadened.

It is further known to produce syndiotactic polypropylene usingmetallocene catalysts as has been disclosed for example inaforementioned U.S. Pat. No. 5,269,807.

Recently, metallocene catalysts have also been employed to produceisotactic polypropylene. Isotactic polypropylene which has been producedusing a metallocene catalyst is identified hereinafter as miPP. Fibresmade of miPP exhibit much higher mechanical properties, mainly tenacity,than typical Ziegler-Natta polypropylene based fibres, hereinafterreferred to as ZNPP fibres. However, this gain in tenacity is onlypartly transferred to non-woven fabrics which have been produced fromthe miPP fibres by thermal bonding. Indeed, fibres produced using miPPhave a very narrow thermal bonding window, the window defining a rangeof thermal bonding temperatures through which, after thermal bonding ofthe fibres, the non-woven fabric exhibits the best mechanicalproperties. As a result, only a small number of the miPP fibrescontribute to the mechanical properties of the non-woven fabric. Also,the quality of the thermal bond between adjacent miPP fibres is poor.Thus known miPP fibres have been found to be more difficult to thermallybond than ZNPP fibres, despite a lower melting point.

WO-A-97/10300 discloses polypropylene blend compositions wherein theblend may comprise from 25% to 75% by weight metallocene isotacticpolypropylene and from 75 to 25% by weight Ziegler-Natta isotacticpolypropylene copolymer. The specification is fundamentally directed tothe production of films from such polypropylene blends.

U.S. Pat. No. 5,483,002 discloses propylene polymers havinglow-temperature impact strength containing a blend of onesemi-crystalline propylene homopolymer with either a secondsemi-crystalline propylene homopolymer or a non-crystallising propylenehomopolymer.

EP-A-0538749 discloses a propylene copolymer composition for productionof films. The composition comprises a blend of two components, the firstcomponent comprising either a propylene homopolymer or a copolymer ofpropylene with ethylene or another alpha-olefin having a carbon numberof 4 to 20 and the second component comprising a copolymer of propylenewith ethylene and/or an alpha-olefin having a carbon number of 4 to 20.

It is an aim of the present invention to broaden the thermal bondingwindow of miPP fibres. It is a further aim of the invention to providenon-woven fabrics of miPP fibres exhibiting improved mechanicalproperties, in particular tenacity.

It is known that polypropylene fibres, and non-woven fabrics made ofpolypropylene fibres, tend to feel rough to the touch. It is also an aimof the present invention to improve the softness of miPP polypropylenefibres.

The present invention provides a polypropylene fibre including at least80% by weight of a first isotactic polypropylene produced by ametallocene catalyst, and from 5 to 20 by weight of a second isotacticpolypropylene produced by a Ziegler-Natta catalyst.

The polymeric fibre may preferably include from 85 to 95% by weight ofthe first isotactic polypropylene and from 5 to 15% by weight of thesecond isotactic polypropylene.

The polypropylene fibre may generally include from 0 to 15% by weight,more preferably from 0 to 10% by weight, of a syndiotactic polypropylene(sPP). The addition of sPP can improve the softness of the fibres aswell as the thermal bonding.

The second polypropylene produced by the Ziegler-Natta catalyst (ZNPP)may be a homopolymer, copolymer or terpolymer or a physical or chemicalblend of such polymers.

The first polypropylene produced by the metallocene catalyst (miPP) is ahomopolymer, copolymer, being either a random or block copolymer, orterpolymer of isotactic polypropylene produced by a metallocene catalystor physical or chemical blend of such metallocene polymers.

Preferably, the first polypropylene has a dispersion index (D) of from1.8 to 4. Preferably, the first polypropylene has a melting temperaturein the range of from 130 to 161° C. for homopolymer and a meltingtemperature of from 80 to 160° C. for a copolymer or terpolymer.

The miPP preferably has a melt flow index (MFI) of from 1 to 2500 g/10mins. In this specification the MFI values are those determined usingthe procedure of ISC 1133 using a load of 2.16 kg a temperature of 230°C.

More preferably, the first polypropylene homopolymer has an Mn of from30,000 to 130,000 kDa and the MFI may range from 5 to 90 g/10 min forspunlaid or staple fibres.

Preferably, the second polypropylene has a dispersion index (D) of from3 to 12. Preferably, the second polypropylene has a melting temperaturein the range of from 80 to 169° C., more preferably a meltingtemperature of from 158 to 169° C. for homopolymer and a meltingtemperature of from 100 to 160° C. for a copolymer or terpolymer. Atypical melting temperature for homo ZNPP is 162° C.

The ZNPP preferably has a melt flow index (MFI) of from 1 to 100 g/10mins.

More preferably, the second polypropylene homopolymer or copolymer has aMFI may ranging from 15 to 60 g/10 min for spunlaid or 10 to 30 g/10 minfor staple fibres.

The sPP is preferably a homopolymer or a random copolymer having a RRRRracemic pentad content of at least 70%. The sPP may alternatively be ablock copolymer having a higher comonomer content, or a terpolymer.Preferably, the sPP has a melting temperature of up to about 130° C. ThesPP typically has two melting peaks, one being around 112° C. and theother being around 128° C. The sPP typically has an MFI of from 0.1 to1000 g/10 min, more typically from 1 to 60 g/10 min. The sPP may have amonomodal or multimodal molecular weight distribution, and mostpreferably is a bimodal polymer in order to improve the processabilityof the sPP.

The present invention further provides a fabric produced from thepolypropylene fibre of the invention.

The present invention yet further provides a product including thatfabric, the product being selected from among others a filter, personalwipe, diaper, feminine hygiene product, incontinence product, wounddressing, bandage, surgical gown, surgical drape and protective cover.

The present invention is predicated on the discovery by the presentinventor that when blended with a major amount of miPP, even in smallconcentrations, ZNPP causes improved thermal bonding of the miPP evenwhen the ZNPP is having a higher melting point than that of the miPP.Accordingly, when blending homopolymer miPP, which has a typical meltingrange of from about 130° C. to about 161° C., with homopolymer ZNPP,which typically has a melting range of from about 159° C. to about 169°C., fibres containing substantially high concentration of miPP exhibitsuperior thermal bonding properties.

The present invention will now be described by way of example only withreference to the accompanying drawings, in which:

FIG. 1 is a stress/strain graph showing the relationship between stressand strain for a typical miPP and a typical ZNPP;

FIG. 2 is a graph showing the relationship between tenacity andcomposition for an miPP/ZNPP blend; and

FIGS. 3 and 4 are graphs showing the relationship between, respectively,elongation (%) at maximum drawing force and fibre tenacity (cN/tex) atmaximum drawing force with respect to miPP amount for fibres producedfrom blends of miPP and znPP.

It is known in the art that fibres with good thermal bonding propertieshave a relatively large elongation at break and show a plateau region inthe stress-elongation curve obtained by tensile tests.

Referring to FIG. 1, it may be seen for a typical miPP, when formed intofibres the miPP has a high tenacity and therefore a high Young's modulus(represented by the relatively steep slope of the stress/strain plot formiPP), and a relatively low elongation at break, typically around 200%.In contrast, for ZNPP, this exhibits a higher elongation at break,typically greater than 400% and a lower Young's modulus, manifested by arelatively shallow slope in the stress/strain graph. Furthermore, at astrain of around 200% the ZNPP typically exhibits a plateau in thestress/strain graph. The higher fibre tenacity obtained with miPPresults from the molecular orientation of a miPP developed duringspinning. It is very likely that the presence of ZNPP in miPP impedesdevelopment of that molecular orientation even at concentrations aroundor below 20% wt. As a consequence, the mechanical properties of miPPfibres are very similar to those of ZNPP fibres even if miPP is the maincomponent of the blend or ZNPP concentration ranging from 20 to 50 wt %of ZNPP. As concentration of Znpp decreases below 20 wt % some molecularorientation typical of miPP can progressively develop in the fibreduring spinning. Accordingly, the fibre tenacity progressively increasesand elongation at break progressively decreases when ZNPP concentrationdecreases.

Referring to FIG. 2, this shows the relationship between tenacity T andfiber elongation E and composition for an miPP/ZNPP blend in apolypropylene fibre. It may be seen that for amounts of miPP of lessthan about 60 to 80% miPP in the blend, the mechanical properties of theblend with respect to tenacity are similar to that for ZNPP. At greaterthan about 90% miPP in the blend, the tenacity is greatly improved, butthis is offset by reduced elongation at break and as a consequence,tendency to have good thermal bonding so that the high tenacity of fibreis not realised in the resultant non-woven fabric. Accordingly, toachieve good mechanical properties in a non-woven fabric, typically themiPP/ZNPP blend includes from 5 to 20 wt % ZNPP.

An industrial thermal bonding process for producing a non-woven fabricemploys the passage at high speed of a layer of fibres to be thermallybonded through a pair of heated rollers. This process thus requiresrapid and uniform melting of the surfaces of adjacent fibres in orderfor a strong and reliable thermal bond to be achieved without destroyingthe molecular orientation developed in the core of the fibre. Theaddition of ZNPP to the miPP despite not lowering the thermal bondingtemperature of the fibres so as to broaden the thermal bondingtemperature range or “window” for the fibres, nevertheless increases theease of thermal bonding the fibres together. Thus the incorporation ofZNPP into miPP enables the maximum strength of the non-woven fabric tobe greatly increased as a result of this increased thermal bondformation between adjacent fibres.

The miPP employed in accordance with the invention has a narrowmolecular weight distribution, typically having a dispersion index D offrom 1.8 to 4, more preferably from 1.8 to 3. The dispersion index D isthe ratio Mw/Mn, where Mw is the weight number average molecular weightand Mn is the number average molecular weight of the polymer. The miPPhas a melting temperature in the range of from 130° C. to 161° C. Theproperties of two typical miPP resins or use in the invention arespecified in Table 1.

The addition of sPP to the miPP also has been found by the inventor toimprove the softness of the fibres. As a result of a surface rejectionphenomenon, the inventor has found that the softness of the fibres maybe increased using only small amounts of sPP, for example from 0.3 wt %sPP in the sPP/miPP/ZNPP blend. Since the blending of sPP into miPPpermits a lower thermal bonding temperature to be employed than would beemployed for pure miPP fibres, and since lower thermal bondingtemperatures tend to reduce the roughness to the touch of a non-wovenfabric produced from the fibres, introducing sPP in accordance with theinvention into miPP improves the softness of the non-woven fabric. Thecomposition of a typical sPP for use in the invention is specified inTable 1.

Furthermore, when sPP is incorporated into miPP to form blends thereof,and when those blends are used to produce spun fibres, the sPP promotesfibres having improved natural bulk, resulting in improved softness ofthe non-woven fabric.

In addition, the use of miPP in blends with ZNPP and optionally sPP inaccordance with the invention tends to provide fibres which can be morereadily spun as compared to known ZNPP fibres. Indeed, the substantialreduction of such long chains in the molecular weight distribution ofthe miPP compared to standard ZNPP tends to reduce built-in stressduring spinning thereby to allow in an increase in the maximum spinspeed for the fibres of the miPP/ZNPP blends in accordance with theinvention.

The incorporation of sPP into the miPP of this invention to form blendsthereof provides a broader thermal bonding window, allowing transfer ofthe properties of the miPP fibres into the properties of the non-wovenfabrics produced from the blends. The thermal bonding temperature offibres produced from such blends is also slightly lower. The fibres andnon-woven fabrics produced from the blends have increased softness andthe spun fibres have natural bulk as a result of the introduction of sPPinto the miPP of this invention. The fibres also have improvedresiliency compared to known polypropylene ZNPP fibres as a result ofthe use of sPP. Furthermore, one use of miPP allows the production offiner fibres, resulting in softer fibres and a more homogenousdistribution of the fibres in the non-woven fabric.

Although it was known prior to the present invention to use a secondpolymer in fibres, it has not heretofore been proposed to employ ZNPP ina blend with miPP for the production of fibres. Efficient thermalbonding of the fibres is required to transfer the outstanding mechanicalproperties of miPP fibres into non-woven fabrics. In addition, onlyaround 5 weight percent of ZNPP is enough to observe a significantimprovement in thermal bondability of the fibres and mechanicalproperties of the non-woven fabrics. As a consequence, the spinnabilityof the fibres produced using miPP/ZNPP blends in accordance with theinvention is not significantly modified as compared to known miPPfibres.

The fibres produced in accordance with the invention may be eitherbi-component fibres or bi-constituent fibres. For bi-component fibres,miPP and ZNPP are fed into two different extruders. Thereafter the twoextrudates are spun together to form single fibres. For thebi-constituent fibres, blends of miPP/ZNPP are obtained by: dry blendingpellets, flakes or fluff of the two polymers before feeding them into acommon extruder; or using pellets or flakes of a blend of miPP and ZNPPwhich have been extruded together and then re-extruding the blend from asecond extruder.

When the blends of ZNPP/miPP are used to produce fibres in accordancewith the invention, it is possible to adapt the temperature profile ofthe spinning process to optimise the processing temperature yetretaining the same throughput as with pure miPP. For the production ofspunlaid fibres, a typical extrusion temperature would be in the rangeof from 200° C. to 260° C., most typically from 230° C. to 250° C. Forthe production of staple fibres, a typical extrusion temperature wouldbe in the range of from 230° C. to 330° C., most typically from 280° C.to 310° C.

The fibres produced in accordance with the invention may be producedfrom miPP/ZNPP blends having other additives to improve the mechanicalprocessing or spinnability of the fibres. The fibres produced inaccordance with the invention may be used to produce non-woven fabricsfor use in filtration; in personal care products such as wipers,diapers, feminine hygiene products and incontinence products; in medicalproducts such as wound dressings, surgical gowns, bandages and surgicaldrapes; in protective covers; in outdoor fabrics and in geotextiles.Non-woven fabrics made with the ZNPP/miPP fibres of the invention can bepart of such products, or constitute entirely the products. As well asmaking non-woven fabrics, the fibres may also be employed to make aknitted fabric or a mat. The non-woven fabrics produced from the fibresin accordance with the invention can be produced by several processes,such as air through blowing, melt blowing, spun bonding or bonded cardedprocesses. The fibres of the invention may also be formed as a non-wovenspunlace product which is formed without thermal bonding by fibres beingentangled together to form a fabric by the application of a highpressure-fluid such as air or water.

The present invention will now be described in greater detail byreference to the following non-limiting examples.

EXAMPLE 1

In accordance with this example, the properties of a non-woven productcomposed of polypropylene fibres incorporating at least 80 wt % miPPwith the remainder being znPP were compared to fibres composed of puremiPP. Thus the pure miPP had an MFI of 32 g/10 mins and a Mw/Mn ratio of3. The znPP had an MFI of 12 g/10 mins and an Mw/Mn ratio of 7. Threeblends, hereinafter called Poly 1, 2 and 3, of the miPP and the znPPwith respective weight ratios of 80 wt % miPP/20 wt % znPP, 90 wt %miPP/10 wt % znPP and 95 wt % miPP/5 wt % znPP were produced. Fibreswere made both of the blends Poly 1, 2 and 3 and of the pure miPP. Thefibres were spun by a long spin process, with the polymer temperature inthe spinnerets being 280° C. The fibre titre after spinning was 2.3 dtexand the fibre titre after drawing was 2.1 dtex. The fibres weretexturised and cut after the drawing step. They were then stored inbales of 400 kg for 10 days. The fibres were then subjected to cardingand bonding at a speed of 110 m/minute. Thereafter, non-woven productshaving a weight of 20 g/m² were produced by thermal bonding. The thermalbonding temperature and the mechanical properties of the non-wovensthereby produced for the Poly 1, 2 and 3 and the pure miPP are shown inTable 2.

It may be seen from Table 2 that the mechanical properties of thenon-woven thermally bonded product of Poly 1, 2 and 3 are greater thanthat for pure miPP at corresponding thermal bonding temperatures.

EXAMPLE 2

In accordance with this example, various blends of znPP and miPP weremade and the compositions of the blends are specified in Table 3.

The miPP had an MFI of 13 g/10 min. The znPP was the same as thatemployed in Example 1. The blends were prepared by dry blending pelletsof the components and pouring the dry blend into the feeder of theextruder immediately after blending. Fibres were then produced from theextruded blend. The fibre was produced using a spinneret having 224holes with a length/diameter ratio of 8/0.8. The extrusion temperaturewas 285° C. with quenching air at 15° C. at a pressure of 50 Pa. Thetemperature of the drawing godets was 80° C. For each blend, fibres wereproduced under the conditions of take-up at 1600 m/min followed bydrawing with a draw ratio (SR) of 1.3. The throughput per hole wasadjusted to keep the fibre titre at around 2.5 dtex.

Table 3 shows the titre, the fibre tenacity at 10% elongation, theelongation at maximum drawing force, the fibre tenacity at maximumdrawing force (sigma@max). FIGS. 3 and 4 are graphs showing therelationship between the elongation at maximum drawing force and thefibre tenacity at maximum drawing force, respectively, with respect tothe amount of miPP in the blend.

Table 4 shows the titre, the fibre tenacity at 10% elongation, theelongation at maximum drawing force, the fibre tenacity at maximumdrawing force (sigma@max) for fibres produced as described here-abovebut without drawing.

It may be noted that for a blend having greater than 80 wt % miPP in theblend of znPP/miPP, the elongation at maximum drawing force and thefibre tenacity at maximum drawing force are substantially increased withrespect to lower miPP amounts. Thus by adding miPP to a znPP/miPP blendin an amount of at least 80 wt % miPP, the mechanical characteristics ofthe fibre are improved, in particular the fibre elongation and tenacity,and in addition, as shown in Example 1, the characteristics of thebonding of the fibres to form thermally bonded non-wovens are improved.

EXAMPLE 3

This example demonstrates the increase in bulk or softness ofpolypropylene fibres by incorporating into the blend of znPP/miPP anamount of sPP.

When polypropylene fibres are laid on a flat surface, such as a glassplate, the morphology of the fibre, in particular its degree ofstraightness or, conversely, its degree of waviness, is an indication ofthe bulk of the fibre. The fibre, which can be examined by opticalmicroscopy, can be seen to have a wavy or substantially sinusoidalmorphology, with increased waviness (i.e. a reduced pitch between peaksof adjacent waves) corresponding to increased bulk or softness of thefibre.

When sPP was added to a polypropylene homopolymer in an amount up to 15wt %, it has been found that the distance between two peaks of the wavysurface decreases, in turn meaning that the bulk or softness of thefibres increases. For example when 5 wt % sPP was blended into aZiegler-Natta polypropylene homopolymer, the distance between the peakswas 5.1 mm whereas when 15 wt % sPP was blended into the samepolypropylene, the distance between the peaks was around 4 mm. Thisdemonstrates that the bulk or softness of the fibres was increased withincreasing amount of sPP in the base polypropylene.

TABLE 1 ZNPP sPP miPP1 miPP2 MI₂ 14 3.6 32 13 Tm ° C. 162 110 and 127148.7 151 Mn kDa 41983 37426 54776 85947 Mw kDa 259895 160229 137423179524 Mz kDa 1173716 460875 242959 321119 Mp kDa 107648 50516 118926150440 D 6.1 4.3 2.5 2.1

TABLE 2 Thermal Bonding Max Force Elong @ break Max Force Elong @ breakTemperature Mach. Dir Mach. dir Trans dir Trans dir Blend (° C.) (N/5cm) (%) (N/5 cm) (%) Poly 1 142 36 95 10 105 Poly 1 148 28 62 14 133Poly 2 142 32 90 11 105 Poly 2 148 28 50 12 117 Poly 3 142 29 50 10 80Poly 3 148 26 40 11 40 Pure miPP 142 13 25 6 20 Pure miPP 148 12 20 6 20

TABLE 3 Take-up: 1600 m/min followed by drawing (SR = 1.3) wt % wt %Titre Tenacity @ 10% Elong @ Sigma @ max znPP miPP (dtex) (cN/tex) max(%) (cN/tex) 100 0 2.6 9.6 407 20.0 80 20 2.6 9.2 379 19.8 60 40 2.6 9.2397 21.5 40 60 2.6 8.9 339 20.7 20 80 2.6 8.8 281 22.3 15 85 2.5 7.8 35223.9 10 90 2.5 8.2 322 26.7 5 95 2.5 8.6 312 29.3 2 98 2.5 9.2 256 31.40 100 2.6 11.5 164 32.3

TABLE 4 Direct Take-up: 1600 m/min wt % wt % Titre Tenacity @ 10% Elong@ Sigma @ max znPP miPP (dtex) (cN/tex) max (%) (cN/tex) 100 0 2.6 6.8435 14.8 80 20 2.6 6.5 513 15.9 60 40 2.5 6.6 456 16.4 40 60 2.6 6.3 46117.1 20 80 2.6 6.1 443 20.3 15 85 2.2 5.8 485 18.9 10 90 2.4 5.8 42420.4 5 95 2.6 5.4 496 20.5 2 98 2.6 5.5 363 24.0 0 100 2.6 6.2 285 27.9

What is claimed is:
 1. A polypropylene fibre including at least 80% byweight of a first isotactic polypropylene produced by a metallocenecatalyst, and from 5 to 20% by weight of a second isotacticpolypropylene produced by a Ziegler-Natta catalyst.
 2. A polypropylenefibre according to claim 1 including from 90 to 95% by weight of thefirst isotactic polypropylene and from 5 to 10% by weight of the secondisotactic polypropylene.
 3. A polypropylene fibre according to claim 1wherein the first polypropylene is a homopolymer, copolymer orterpolymer of isotactic polypropylene or a blend of such polymers.
 4. Apolypropylene fibre according to claim 3 wherein the first polypropylenehas a dispersion index (D) of from 1.8 to
 4. 5. A polypropylene fibreaccording to claim 3 wherein the first polypropylene has a meltingtemperature in the range of from 80 to 161° C.
 6. A polypropylene fibreaccording to claim 1 wherein the first polypropylene has a melt flowindex (MFI) of from 1 to 2500 g/10 mins.
 7. A polypropylene fibreaccording to claim 6 wherein the second polypropylene has a dispersionindex of from 3 to
 12. 8. A polypropylene fibre according to claim 1wherein the second polypropylene has a melting temperature in the rangeof from 80 to 169° C.
 9. A polypropylene fibre according to claim 1further comprising up to 15% by weight of a syndiotactic polypropylene(sPP).
 10. A polypropylene fibre according to claim 9 comprising up to10% by weight of a syndiotactic polypropylene (sPP).
 11. A polypropylenefibre according to claim 10 wherein the sPP is a homopolymer, a randomcopolymer, a block copolymer or a terpolymer or a blend of suchpolymers.
 12. A polypropylene fibre according to claim 10 wherein thesPP has a melting temperature of up to about 130° C.
 13. A fabricproduced from the polypropylene fibre according to claim
 1. 14. Aproduct including a fabric according to claim 13, the product beingselected from a filter, personal wipe, diaper, feminine hygiene product,incontinence product, wound dressing, bandage, surgical gown, surgicaldrape, geotextile, outdoor fabric and protective cover.